Crosscut fiber and method for its preparation



Jan. 8, 1957 J. D'A. CLARK 2,776,688

CROSSCUT FIBER AND METHOD FOR ITS PREPARATION Original Filed March 23,1953 2 Sheets-Sheet 1 ATTORNEYS.

' Jan. 8, 1957 .1. DA. CLARK 3,77$,538

CROSSCUT FIBER AND METHOD FOR ITS PREPARATION Original Filed March 25,1953 Q 2 Sheets-Sheet 2 v J I 11 iii L 3/ 1 I L Z 7/ INVENTOR.

am 62% (gm ATTORNEYS.

CROSSCUT FIBER AND METHOD FOR ITS PREPARATION James dA. Clark, Victoria,British Columbia, Canada, assignor to Chaugewood Corporation, Chicago,11]., a corporation of Illinois Original application March 23, 1953,Serial No. 344,089. gigidoed and this application July 18, 1956, SerialNo.

Claims. 01.144-309 This invention relates to a new and improved woodparticle and it relates particularly to a woody fibrous element andmethod for manufacturing same, and to a consolidated productmanufactured therefrom andmethod for manufacturing same. t s

This isa division of my copendingapplication Serial United States Patent0 No. 344,089, filed March 23, 1953, and entitled Crosscut Fiber andMethod for its Preparation.

In Patent No. 2,689,092, description is made of the manufacture of afiber flake or wafer cut crosswise tangentially to the grain of the woodand having end faces formed at right angles to the sides and to the topand bottom faces of the wafer. Unless such flakes or wafers are cutundesirably thin, the abrupt vertical end faces of the wafers causeundesirable zones or lines of weakness throughout the structure moldedtherefrom. This is particularly evident with harder woods and woodshaving hard summer wood annual rings, such as are found in SouthernPines. Moreover, on the broad faces of well compacted structures moldedtherefrom and particularly where the end of one waferoverlaps the faceof another, there exists an undesirable linear depression which not onlyconstitutes a line of weakness upon flexure but presents an unattractiveappearance and provides a crevice wherein dirt may lodge. The sideportions of flakes of this type do not present the same diflicul-tiesbecause the side surfaces are predominantly parallel to the annual ringswhich are usually at an acute angle to the broad surfaces. Further, bybeing parallel to the grain, the side faces and edges are more pliablelaterally than are the end faces and edges. Consequently the juncturebetween the side edges and the underlying. element does not becomeobvious nor objectionable in the molded structure. I

An object of this invention is to provide an improved wood fiber orflakesuitable for manufacturing molded fibrous products. I

. Another object is to provide-fibers .or flakes of woody materialcharacterized by theirability to form asmooth, continuous unbrokensurface and which become well joined with underlying fibrous elementsduring molding into a consolidated product. 1

A further object is to provide a method for producing wafers suitablefor forming into strong and attractive consolidated products by the useof brittle woody material, such as ,kiln dried lumber. x

' Another object is' to provide a method of producing woody flakes orwafers of predetermined thickness and length with ends of the'flakestapered or wedge shaped.

A still further object is to produce a strong consolidated fibrousproduct of high density having a substantially unbroken surface by theuse of woody flakes or wafers advantageously shaped and thinly coatedwith resinous material. p

These and other objects and advantages of this invention willhereinafter appear and for purposes of illustration, but not oflimitation, an embodiment of the invention is Shown in the accompanyingdrawings, in which i t Figure 1 is a perspective view of a woody flakeproduced in accordance with this invention;

Figure 2 is a sectional view taken along the line 22 of Figure l; I

Figure 3 is a sectional view taken along the line 3-3 of Figure 1;

Figure 4 is a plan view of a modified form of flake produced inaccordance with this invention;

Figure 5 is a sectional view taken along the line 5-5 of Figure 4;

Figure 6 is a perspective view of a further modification in a woodywafer or flake embodying features of this invention;

Figure 7 is a perspective view showing a still further modification in aflake or wafer embodying features of this invention;

Figure 8 is a schematic side elevational view of an apparatus which maybe used in preparing flakes in accordance with this invention;

Figure 9 is a plan view of the apparatus shown in Figure 8;

Figure 10 shows a grouping of knife elements which may be used in themanufacture of wafers of the type shown in Figure 6;

Figure 11 indicates a grouping of knife elements adapted to manufactureflakes of the type shown in Figure 7;

Figure 11A shows another grouping of knife elements which may also beused to manufacture flakes of the type shown in Figure 7; t

Figure 12 is a fragmentary view of the surface of a composite fibrousstructure, made of wafers having their end edges perpendicular to thesides, and

Figure 13 is a fragmentary view of a composite fibrous structure madewith wafers having end edges at an oblique angle with the sides.

In accordance with this invention, wafers or flakes are cut from awooden block by cutting into the block of wood parallel to the length offibers in the wood preferably by feeding the block of wood towards amoving cutting edge substantially perpendicularly to its path and with acutting movement transverse said length to form wafers having athickness corresponding to the depth of cut by scoring the wood withangular cuts in the direction of cutting movement. For this purpose,wafers or flakes are cut from a wooden block by knife elements which arearranged substantially parallel to the length of the fibers duringcutting operations to form the broad faces while the end faces aresevered at acute angles with the broad faces to impart the desired taperand flexibility to the ends for the purpose of enabling the manufactureof a strong, smooth-faced consolidated product. By feeding the blockperpendicularly to the path of the cutting edge the wafers or flakesproduced will have parallel broad faces.

As shown in Figures 8and 9, a succession of wooden blocks 20 having atleast one end squared is positioned on two endless chains 21 with thesquared end 22 abutting the side wall 23. Each conveyor chain 21 isendless and passes over an idler sprocket 25 at one end and a drivesprocket 24 at the other, the latter of which is driven through afriction clutch 26 by a variable speed motor 27. Dogs 28 spaced alongthe length of the chain 21 function in a manner to advance the woodenblocks 20 past a circular saw member 29 which severs the block topredetermined length so as to enable further passage with the chainsbetween side walls 23 and 30.

A pair of horizontally disposed downwardly inclined disk members 31having serrated or toothed edges 32 extend through a slot in the sidewall members 23 and 30 beyond the idler sprocket 25 so as to compressand grip the ends of the block 20 therebetween as it is fed to them .bythe chain 21 and advance them toward a cutting'drurn 33. The diskmembers 31, rotated by a variable speed driving motor 34, take over thefeed of the wooden block toward the cutting knives 35 peripherallyarranged about the cutting drum 33.

With the feed wheels or disks 31 located immediately in advance of thecutting wheel 33 and in constant engagement with the wooden block whileit is being cut and, with the downward slant of the disk, a steady feedrate of variable speed is secured without chatter or excessive vibrationwhich would otherwise occur if the feeding of the block were performedby the dogs on the belt. The downward slant of the disks ensures thatthe block is kept firmly pressed against the bed plate 36, because theteeth in the disks thereby bite downwardly as well as inwardly, as theblocks are fed forward.

The cutting drum 33 is rotatably mounted on the shaft 36' which isadapted to be driven at variable speed from a power source (not shown).A plurality of knife elements 35 are substantially equidistantlyarranged about the periphery of the wheel with the cutting edgesextending from the surface thereof to effect severance of the block intowafers or slivers of the type which will hereinafter be described. Bythe proper selection and arrangement of knife elements, it has beenfound possible to sever wafers of predetermined contour in a singleoperation by the cutting drum 33.

In the modification shown in Figure 10, the alternate rows of knifeelements are formed with cutting edges Q having a length less than 5inches and spaced laterally one from the other in the cutting element bya distance corresponding to the length of the cutting edges. The endcorners of the cutting edges Q are sloped laterally from the outer endof the cutting edges to the base. The cutting elements in between areformed with cutting edges P dimensioned to correspond to the cuttingedges Q but arranged to extend across the space left vacant by thecutting edges Q in the preceding cutting element. The end corners of thecutting edges P are also similarly tapered out laterally from thecutting edge to the base.

In operation, the cutting edges Q, which come into contact with theblock of wood, operate more or less to route out wafers from the woodenblock having a length, when measured in the grain direction,corresponding to the length of the cutting edge and a thicknesscorresponding to the depth of cut. The ends of the wafers will betapered more or less corresponding with the slope at the end corners ofthe cutting edges. The cutting edges leave grooves in the face of thewooden block spaced one from the other by a distance corresponding tothe spaced relation between the cutting edges Q. The cutting edges P ofthe oncoming cutting element level the face of the block by cutting toan equivalent distance into the block thereby to sever the raisedportions and form wafers dimensioned to have a length corresponding tothe length of the cutting edges and a thickness corresponding to thedepth of cut. When the corners of both sets of blades Q and P aretapered as described, wafers of the type shown in Figure 6 will beproduced.

In the modification shown in Figure 11, alternate cutting elements areused with one group having cutting edges R corresponding to the cuttingedges Q of the previously described modification. The alternate cuttingelements in between comprise blades having cutting edges S extendingcontinuously across the drum.

In operation, the cutting edges R cut into the face of the wooden blockto route out wafers having a length in the grain direction correspondingto the length of the cutting edges and a thickness corresponding to thedepth of cut. The ends of the wafers in the grain direction are taperedto correspond with the slope at the end corners of the cutting edges.The oncoming cutting element S cuts to the same depth as the previouscutting edges R thereby to shave off material that is left in the faceof the wooden block between the edges R of the previous cutting element.

When an arrangement of the type described in Figure 11 is employed,wafers of the type shown in Figure 7 of the drawings will be produced.

In the modification shown in Figure 11A, one set of cutting elements isformed with triangularly shaped cutting elements T spaced one from theother by a distance corresponding to the length of the wafers to be cutwhen measured in the grain direction. The triangular cutting elements Tgouge out a triangularly shaped section from the face of the woodenblock having a depth corresponding to the thickness of the wafers to becut and with the apex of the groove in the center. The oncoming set ofcutting elements is formed with cutting edges U extending continuouslyacross the drum and arranged to cut to a depth corresponding to thegouged-out portion in the face of the wooden block thereby to cut wafersfrom the block having a thickness corresponding to the depth of cut anda length corresponding to the distance between the grooves. The watersthat are formed will have tapered ends, as illustrated in Figure 7 ofthe drawing.

The length of the wafers will correspond to the distance between theoutwardly directed cutting edges or depressions in the knife elementswhile the width of the wafers will correspond to the thickness of thewooden block except for the splitting that normally occurs lengthwisealong the grain which subdivides the wafer into widths usually an inchor less. The thickness of the wafer depends upon the linear rate of feedof the block as governed by the rotational movement of the disk members31 and the peripheral speed of the cutting knives 35 which successivelyengage the block. Increasing the rate of feed of the block willcorrespondingly reduce the thickness of 1 the wafers and vice versa. Foruse in the manufacture of invention, exemplified in Figures 1 to 5, havewedgeshaped ends formed by end faces ABHG or CDFE, a controlledthickness DJ, length AD and width DC, the end faces making an acuteangle DAG or DEG with the top and bottom faces ABCD or HFEG. The endfaces DCFE and ABHG may be markedly curved if the edges of the sides ofthe depressions in the cutters shown in Figures 10, 11 and 11A aresimilarly curved.

In general, the side faces ADEG and BDFH will be neither fiat norexactly parallel to the length of the fibers because they will usuallyconstitute fractured surfaces along natural striae as those between theannual rings in wood. However, either face may have been a part of theouter face of the billet of wood from which the wafer was cut. Thisabsence of parallelism or regularity between the pairs of side faces ofthe majority of the wafers and the parallelism of each side face withthe adjacent annual ring inthe wood, serves in part to distinguishwafersv made in accordance with this invention from others. For example,it i understood that thin decorative wafers. have been sliced obliquelyfrom the end of a stick of wood with the grain running the short way. Insuch a case, except for inadvertent fractures the end and side faces ofthe wafers so made will comprise parts of the four outer fiat faces ofthe original stock of wood from which they were cut.

When the broad top and bottom surfaces of the wafers have been cut witha knife edge lying parallel to and moving across the direction of thefibers as herein described; the original strength of the fibrouselements in the woody structure is preserved almost intact. If, on theother hand, the cutting edge lies at an angle to or moves in other thana direction substantially perpendicular to the axial direction of thefibers, the resulting wafers, especially if cut from air dry wood, willbe more or less checked or cracked across the grain, as is very evidentwith ordinary planer shavings. The direction in which the faces offibers have been cut may be determined from microscopic observation, byseeing in which direction lie the scratches made by imperfections in thecutting edges and the direction in which microscopically small fibrouselements have bent while being cut.

Elements or wafers made in accordance with this invention, having athickness of upwards of 0.002 inch, from 1.0 to 2.0 inches long and ofvarious widths, are particularly suitable for use in preparing acomposite molded fibrous structure. This is preferably accomplished bydusting or mixing the wafers with a small percentage of finely powderedthermoactive resin, such as phenol formaldehyde, urea formaldehyde,melamine formaldehyde and the like curable thermosetting resins in anintermediate stage of polymeric growth, and felting the resultingresinous coated wafers into a mat, such as described in my copendingapplication Ser. No. 110,212, filed August 13, 1949, now Patent No.2,698,271. The desired resinous concentration in uniform distribution onthe surfaces of the wafers can also be accomplished by treating thefibrous elements with resinous solution and dispersion and drying beforefelting or by the addition of such bonding agents in combination withthe felting operation. When using dry powdered resin with wafers of thetype described, it has been found that from 2-4 percent resin willproduce molded boards having strength proper-ties which are considerablygreater than that heretofore secured with 10-40 percent by weight resinadded to conventional fine wood fibers or to sawdust. The amount ofresin required for molding into a composite board is dependent upon thethickness of wafers and the density of the wood of which they are formedbut with the thicker wafers more than 3 percent by weight resin isseldom if ever required. It is believed more accurate to define theresin concentration in relation to the amount present per unit area offiber surface because of the variation in proportion to the thicknessand the density of the wafer. Under such circumstance it has been foundthat amounts within the range of A -l pound dry resin per 1000 squarefeet of surface area is sufiicient for consolidation to produce boards,which is only a small fraction of the amount heretofore required toproduce a molded board of comparable strength with materials of theprior art. Further increases in the amount of resin are not necessarybecause it does not proportionately increase the strength of the moldedproduct.

By way of example, wafers about 0.015 inch thick made in accordance withthis invention from a moderately hard wood like Douglas Fir are dustedwith 3 percent by weight of phenolic resin (minus 200 mesh) (about 0.52pound per 1,000 square feet of surface area). The resinous coated wafersare felted into a mat and consolidated under pressure of 500 p. s. i.for minutes at 320 F. A /4 inch board having a density of 1.0 and amodulus of rupture of over 7,000 p. s. i. is obtained. If a polishedcaul is used during the consolidation of molding of the board, the faceof the board formed against it is characterized further by having asmooth, glossy surface unmarred by linear depressions at the ends of thewafers. The board is further characterized by substantially all of thevisible wafers having their side edges parallel to the grain of thewood, as shown in the fiber-s in Figures 3 and 5 and by the fragmentaryplan views of the boards in Figures 12 and 13.

If the knives cutting the wafers to length are dull, the end edges ofthe wafers will be ragged. This ragged or scalloped effect of the endedges is often achieved when the surface lamina of a structure composedof wafers having sharp straight end edges, is sanded. Removal of thesurface by sanding, of course, removes also the resinous glossy surface.

Particularly when the wafers are cut from hard wood or wood having densesummer wood rings, wafers having ends tapered in thickness give astronger and considerably smoother surfaced board than do wafers havingblunt endsf Furthermore; this tapering of the ends permits a thickerwaferto be used than if the ends were not "tapered. In consequence, thespecific surface of the fibrous material is reduced and with thisproportionately the quantity of resinous binder necessary to make aboard having a required strength.

' The use of a single cutting drum having knives of the type illustratedby Figures 10 and 11 provides fibers which are immediately cut todesired contour in a onestep operation.

By permitting the knives on the sliver cutters to protrude only a littlemore from the face of the cutter than the thickness of the slivers to becut, when the side end of a billet of wood is reached, there iscomparatively little disturbance to the cutting. By positively feedingthe billets of wood to the cutter as close as possible to it as hereindisclosed, not only is the thickness of unsupported side ends of thebillets reduced to a minimum, but the absence of the springiness betweenthe cutter and the feeding means of a comparatively long length of woodor pieces of wood, markedly improves the uniformity of thickness of theslivers and their smoothness of surface. Both these improvements resultin an appreciable reduction in the quantity of resin and sizingnecessary for making a structure of a required strength and resistanceto liquids.

It is to be understood that the apparatus shown and described is to betaken as exemplary only of the method disclosed for producing animproved wafer of high quality and at a comparatively low cost frompieces of woody material that otherwise might be of little value.

It will be further understood that numerous changes may be made in thedetails of construction, arrangement and operation of the apparatuswithout departing from the spirit of the invention, especially asdefined in the following claims.

I claim:

I. The method of producing fibrous wafers of the type described,comprising the combination of steps of cutting a block of wood parallelto the lengths of the fibers in the wood with a first cutting movementtransverse said lengths to produce slots in the face of the wood spacedapart in the direction of the lengths of the fibers by an amountcorresponding to the lengths of the wafers subsequently to be cut fromthe block of wood, the sides of said slots being sloped inwardly bycutting in said first cutting movement at an angle in the edges of saidslots, and cutting the block of wood parallel to the lengths of thefibers in the wood with a second cutting movement transverse saidlengths and at a depth corresponding to the depth of the slots to severthe portions in the face of the wooden block between said slots to formtapered end wafers having a thickness corresponding to the depth of cutand lengths corresponding to the spaced relation between the slots.

2. The method of producing fibrous wafers of the type described,comprising the combination of steps of cutting a block of wood parallelto the lengths of the fibers in the wood with a first cutting movementtransverse said lengths in transversely spaced-apart portions in saidblock of wood and in an angular relation at the lateral edges to producetapered end wafers having lengths in the fiber direction correspondingto the depth of cut with tapered end sections leaving fiat slots inlaterally spaced-apart portions in the block of Wood dimensioned to havea width corresponding to the lengths of the wafers that are cut andsloping sides corresponding to the taper in the ends of the wafers, andcutting the block of wood parallel to the lengths of the fibers in thewood with a second cutting movement transverse said lengths to severmaterial between the slots from the face of the block of wood to formwafers having tapered ends and dimensioned to have lengths in the fiberdirections corresponding to the spaced relation between the slots.

3. The method of producing fibrous wafers as claimed in claim 2 in whichthe slots have a width less than 5 inches but greater than 0.5 inch toform wafers in the first cutting movement dimensioned to have lengths inthe fiber directions corresponding to the width of the slots.

4. The method of producing fibrous wafers as claimed in claim 2 in whichthe spaced relation between the slots is less than 5 inches but greaterthan 0.5 inch to form 8 wafers by the second cutting movement havinglengths in the fiber direction of corresponding dimension.

5. The method as claimed in claim 2 in which the wooden block isadvanced substantially perpendicularly to the direction of cuttingmovement whereby wafers are cut with substantially parallel broad faces.

References Cited in the file of this patent UNITED STATES PATENTS2,751,947 Wyss June 26, 1956

